Petrus (Pieter) Smidt, born 10 November 1707, at Amsterdam, died there 12 August 1781, whose great-grandfather was Gerrit Smidt, a Mennonite preacher of Hamburg-Altona, was an elder of the Amsterdam Zonist congregation from 1728 until his death. When the Amsterdam Lamist congregation started a seminary for the training of Mennonite ministers and some Zonists desired a good training for their ministers too, the Amsterdam Zonist congregation decided to open a Zonist seminary, appointing Petrus Smidt as theological professor in 1753. Smidt taught until 1780, when the Zonist seminary was closed; the number of students had always been very small. Smidt did not publish any writings except a sermon in 1728.

Petrus Smidt seems to have been a man of means. Besides a stately home at Amsterdam, first on the Singel, later on the Heerengracht, he owned a country home at Uithoorn. He married Sara de Koker (1702-58). His daughter Maria Smidt was married to Pastor Hendrik van Gelder, whose descendants, still numerous in the Netherlands, bear the family name of Smidt van Gelder.